Covering-thread mechanism for sewing machines



A. H. M VOE. COVERING THREAD MECHANISM FOR SEWING MACHINES.

APPLlCATION FILED SEPT. 22, 191 7- 1,403,897, Patented Jan. 17, 1922.

INVENTOR j $6M W- UNITED STATES PATENT OFFICE.

ALBERT H. DE VOE, OF WESTFIELD, NEW JERSEY, ASSIGNOR TO THE SINGER MANU- FACTURING COMPANY, A CORPORATION OF NEW JERSEY.

COVERING-THREAD MECHANISM FOR SEWING MACHINES.

Application filed September 22, 1917.

To all whom it may concern:

Be it known that I, ALBERT H. DE Von, a citizen of the United States, residing at \Vestfield, in the county of Union and State of New Jersey, have invented certain new and useful Improvements in Covering Thread Mechanisms for Sewing Machines, of which the following is a specification reference being had therein to the accompanying drawings.

This invention relates to sewing machines, more particularly of the multiple-needle type, and has for an object to provide an improved mechanism for laying or looping a covering thread back-and-forth in advance of theyneedle or needles; which mechanism shall be simple, wear-resisting and capable of long continued and efiicient operation at high speed.

A further object of the invention is to provide a simplified covering thread mechanism, the operation of which is substantially inde pendent of the thickness of the work.

The invention, in its preferred form, is embodied in a plural-needle chain-stitch machine; the needles cooperating with the usual thread-carrying looper disposed below the throat-plate. The covering thread is guided to an eyed thread-finger which is preferably mounted at the lower end of a thread-finger lever pivoted to a bracket fixed to the presserbar and is adapted to'oscillate in a vertical plane parallel with and at one side of the line of feed. A spreader-finger is mounted on said bracket to oscillate to-and-fro in front of the needles about a vertical axis and carry a loop of covering thread-across the line of seam where it is detained for penetration by the adjacent needle. The thread-finger and spreader are so connected that, as the eyed thread-finger moves rearwardly, the spreader moves across in front of the needles. The thread-finger and spreader are actuated by a simple wear-resisting and dwell-producing connection with the needle-actuating means; said connection comprising, in the present instance, a sleeve surrounding the upper endportion of the thread-finger lever and pivotally mounted on a crank-pin carried by the needle-actuating rock-shaft. Preferably, the parts are so arranged that when the needlebar is at the end of its up-stroke, the upper end-portion of the thread-finger lever will be parallel'with' the presser-bar and substantially tangent to the curved path of move- Spccification of Letters Patent.

Patented Jan. 17, 1922.

Serial No. 192,675.

ment of the' actuating sleeve, whereby a dwell of the thread-finger and spreader will be produced during the first part of the down-stroke of the needles; said dwell being independent of the thickness of the work and the consequent vertical position of the thread-handling implements carried by the presser-bar. Thus the timing of the threadhandling implements is independent of the vertical position of the presser-foot as determined by the thickness of the work being stitched.

In the accompanying drawings, Fig. 1 is a front end elevation of a machine head embodying the present improvement. Fig. 2 is a front side elevation of the mechanism with the head of the machine in section. Fig. 3 is an elevation of the lower part of the mechanism looking in a direction opposed to'that shown in Fig. 1. Fig. 4: is a front elevation of the mechanism removed from the machine. Fig. 5 is a horizontal section on the line 55, Fig. 3. Figs. 6 and 7 are perspective views illustrating the manner in which the covering thread is handled and presented to the needles and Fig. 8 is a rear elevation of the mechanism removed from the machine.

In the preferred embodiment of the invention, as illustrated, the machine is or may be provided with stitch-forming mechanism constructed substantially in accordance with the disclosure in my United States Patent No. 1,100,124, an additional needle being added, in the present instance, to cooperate with the single looper disclosed in said patent. In the embodiment illustrated, therefore, the stitch-forming mechanism comprises a pair of reciprocating needles n and n carried by the needle-bar 1 which is journaled in bushings 2, 2, fixed in suitable hearing apertures provided therefor in the usual head 3 of the sewing machine frame. The needle-bar 1 is actuated by means of the link 4 connected to the crank-pin 5 sustained by the crank-arm 6 mounted on the needle-actuating rock-shaft 7. Cooperating with the needles n and 12 in the usual manner to form stitches, is a loop-taker 8 having, in the present instance, the form of an ordinary thread-carrying looper.

The resser-bar 8 is journaled in the head 3, in rear of the needle-bar, and has secured to its lower end the presser-foot shank 9 to which is pivotally secured at 10 the presserfoot sole-piece 11 adapted to press the work 7 upper end of the presser-bar is the usual leaf-spring 12. Slidably mounted upon the presser-bar within the head 3 is a lifting block 13 carrying a roller-stud 14 which is adapted to be acted upon by the usual lifting cam-lever 15. The block 13 also carries a lateral'pin 16 which may be acted upon by means of the forward end 17 of a treadle controlled lifting lever. Motion of the lifting block 13 is imparted to the presser-bar through the collar-block 18 fixed to said bar and disposed above the ledge 19 formed on .said lifting block 13.

Clamped to the presser-bar 8, below the head 3, is a split lug 20 of a bracket 21 in which is journaled the vertically disposed shank 22 of the spreader 23 the lower extremity. of which is formed with a threadengaging hook 24 adapted to pass back-and forth in front of the needles. The bracket 21 is formed with an upward extension the forwardly curved upper extremity 25 of which carries a lateral sleeve 26 in which is journaled the fulcrum-pin 27 projecting laterally from the thread-finger lever 28. The upper end of the lever 28 is apertured to receive the rounded extension pin 29 which is embraced by a sliding sleeve 30 formed with a lateral boss 31 apertured to fit about the crank-pin 32 carried by the needle-actuating shaft 7.

The lower extremity of the thread-finger lever 28 1s provided with a longitudinally extendmg groove or way 33 to which is fitted the shank 3 1 of the thread-finger 35.

A screw 36 is threaded into said shank and passes through a slot 37 in the lever 28, thus serving to secure the thread-finger to its supporting lever while permitting adjustments of said thread-finger longitudinally of said lever. In the present instance, the thread-finger 35 is extended forwardly, downwardly, rearwardly and thence laterally, to clear the spreader 23, and is provided with a thread-eye 38.

Secured to the upper end ofthe fulcrumshank 22 of the spreader 23 is a short crankarm having a ball extremity 39 embraced by one end of the short link 40 the opposite end of which embraces the ball-ended pin -41 carried by and projecting laterally from the lever 28. It will be clear from the foregoing descriptionthat when the lever 28 is v1brated to move the thread-finger 35 for- ,wardly and rearwardly, motion will be transmitted through the link 40 to the spreader 23 which will accordingly be vibrated laterally across the line of seam in advance of the needles.

Inthe operation of the device, when the needles are at the lower end of their stroke,

.Fig. 6, the thread-finger 35 assumes its extreme forward position and the spreaderfhook 2e has moved across the path of the covering-thread leading from the last stitch to the eye 38 of the thread-finger and lies at the right of said thread. As the needles rise, the spreader-hook 24 moves to the left and carries a bight .of covering thread with it. At the same time the thread-finger 35 moves rearwardly and downwardly. At the end of the up-stroke of the needles the spreader 23 .has moved to its extreme left-hand position and the thread-finger 35 has moved across the plane of the needles, and lies in its extreme rearward position. As the needles descend, the feed having taken place as usual, the spreader and thread-finger dwell in their extreme loop-presenting positions, Fig. 7, (the crank-pin 32 moving substantially vertically at this time) wherein the spreader presents a loop for entry by the needle 71 while the thread-finger 35 holds the covering thread in rear of the path of the needle 0?? and close to the surface of the" work. Since the thread-handling devices 23 and 35 are sustained by the presser-foot carrier or bar, it is apparent that the exact course of the covering thread from the last stitch, around the spreader-hook 24, and through the thread-eye 38, will be maintained in a fixed correct relation relatively to the path of the descending needles and'to the surface of the work, regardless of the works thickness.

It will be readily understood by those skilled in theart that the in-vention herein disclosed is susceptible of various embodiments diifering from thes'pecific embodiment shown and described yet falling within the spirit and scope of the invention.

Having thus set forth the nature of the invention, what I claimiherein is 1. In a sewing machine, in combination,

a presser-bar, a bracket carried by said. presser-bar, a thread-finger lever fulcrumed to said bracket, a thread-finger element carried by said lever, a spreader element also fulcrumed to said bracket the fulcrums being disposed at an angle to each other and on the same side of the presser-bar, a connection between said thread-finger and spreader elements, and means for, actuating one of said elements.

2. In a sewing machine, in combination, stitch-forming mechanism including a plu'- rality of reciprocating needles and complemental loop-taking means, a resser-bar, covering thread laying mechanism sustained by said bar and comprising an eyed threadfinger movable along the line of seam at one side of the needlesand a hooked threadfinger adapted to engage the covering thread and carry a loop thereof across the line of seam, an operative connection between said thread-fingers whereby they are caused to operate in unison, and aQdwell-producing driving connection with one of said fingers stationary during the first part of the downstroke of the needles.

3. In a sewing machine, in combination, a reciprocating needle-bar and a needle carried thereby, a spring-pressed resser-bar and a presser-foot carried thereby, a worksupport, covering thread handling means sustained bysaid presser-bar, means for actuating said thread-handling means including a sliding driving connection angularly movable with respect to the presserbar and adapted to assume a position substantially in parallelism therewith during the first part of the down-stroke of the needle, whereby said thread-handling means maintains the same loop-presenting.position relatively to the needle-path and the upper surface of the Work regardless of the works thickness.

4. In a sewing machine, in combination, a reciprocating needle, a work-support, a resser-foot opposed to said work-support, a presser-foot carrying element, threadhandling means adapted to present a loop of covering thread for entry by said needle,

means connected with said presser-foot for maintaining said thread-handling means at a fixed elevation above the upper surface of the work, and means for actuating said thread-handling means including a dwellproducing sliding driving connection adapted to assume a position substantially in parallelism with the resser-bar during the first-part of the down-stroke of the needle.

5. In a sewing machine, in combination, a presser-bar, covering thread laying mechanism carried thereby and comprising an interconnected finger and spreader, and a dwell-producing slidable driving connection for said covering thread laying mechanism.

6. In a sewing machine, in combination, a resser-bar, a lever carried thereby and having a thread-finger thereon, a spreader element also carried by the resser-bar and interconnected with the lever, an actuating rock-shaft, and a sliding dwell-producing member connecting said rock-shaft and lever.

In testimony whereof, I have signed my name to this specification.

ALBERT H. DE VOE. 

